feature symfony#1502 add vietnamese translation (sungvadan)

This PR was squashed before being merged into the main branch.

Discussion
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add vietnamese translation

Hello,

This is "Vietnam" language translation.

Commits
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4060b74 add vietnamese translation

Author: javiereguiluz

config/services.yaml

@@ -6,7 +6,7 @@
 parameters:
     locale: 'en'
     # This parameter defines the codes of the locales (languages) enabled in the application
-    app_locales: ar|en|fr|de|es|cs|nl|ru|uk|ro|pt_BR|pl|it|ja|id|ca|sl|sq|hr|zh_CN|bg|tr|lt|bs|sr_Cyrl|sr_Latn|eu|ne|bn
+    app_locales: ar|en|fr|de|es|cs|nl|ru|uk|ro|pt_BR|pl|it|ja|id|ca|sl|sq|hr|zh_CN|bg|tr|lt|bs|sr_Cyrl|sr_Latn|eu|ne|bn|vi
     app.notifications.email_sender: [email protected]
 
 services: